MUMBAI, April 21 (Reuters) - The Indian rupee fell to a three-and-a-half month low on Tuesday and stocks sank to their lowest in nearly four weeks on concerns about foreign outflows after Japan's Daiichi Sankyo's $3.6 billon share sale in India's Sun Pharmaceutical Industries.

Daiichi Sankyo began the sale late on Monday, according to a person directly involved in the deal and a marketing term sheet seen by Reuters.